Cathedral or ‘Katedra’ is a short film based on a short story by Polish science fiction author Jacek Dukaj back in 2000. It was nominated for the Oscar in 2002 in the Animated Short Film category. Tomasz Bagiński made this, and at 6 minutes and 28 seconds manages the considerable feat of being both watchable and intelligent. I highly recommend you check it out:

If, after watching that, you are hungry for further information, Kuriositas.com has a great feature on this under-seen piece.